Variable geometry thruster

ABSTRACT

A propulsion system coupled to a vehicle. The system includes a diffusing structure and a conduit portion configured to introduce to the diffusing structure through a passage a primary fluid produced by the vehicle. The passage is defined by a wall, and the diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid. A constricting element is disposed adjacent the wall. An actuating apparatus is coupled to the constricting element and is configured to urge the constricting element toward the wall, thereby reducing the cross-sectional area of the passage.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Application No.62/379,711, filed Aug. 25, 2016, and U.S. Provisional Application No.62/380,108, filed Aug. 26, 2016, the entire disclosures of which arehereby incorporated by reference as if fully set forth herein.

INCORPORATION BY REFERENCE

U.S. patent application Ser. No. 15/670,943 filed Aug. 7, 2017, U.S.patent application Ser. No. 15/654,621 filed Jul. 19, 2017, U.S. patentapplication Ser. No. 15/221,389, filed Jul. 27, 2016, U.S. patentapplication Ser. No. 15/221,439, filed Jul. 27, 2016, and U.S. patentapplication Ser. No. 15/256,178, filed Sep. 2, 2016 are herebyincorporated by reference in their entireties as if fully set forthherein.

COPYRIGHT NOTICE

This disclosure is protected under United States and InternationalCopyright Laws. © 2017 Jetoptera. All rights reserved. A portion of thedisclosure of this patent document contains material which is subject tocopyright protection. The copyright owner has no objection to thefacsimile reproduction by anyone of the patent document or the patentdisclosure, as it appears in the Patent and Trademark Office patent fileor records, but otherwise reserves all copyrights whatsoever.

BACKGROUND

It has been demonstrated in tests that conditions in which there is lessthan optimal primary fluid flow supplied to an ejector/thruster, theoperation in the round ends of the thruster or ejector remains veryperformant. However, the straight portion of the thruster is where theprimary fluid injectors suffer a rapid performance degradation. Testsshow that the efficiency of the thruster declined significantly withlower flow, yet measurements of the velocity of the mixedentrained/primary fluids efflux from the two ends of the thruster remainhigh even at low flows. In one test the velocity measured behind theround ends of the thruster at about one length of the ejector downstreamof its exit plane remained in excess of 200 mph, whereas in the middleof the thruster corresponding to the straight or linear geometry, thevelocity dropped to less than 100 mph. This is due to the specific flowpattern and the configuration of the rounded ends of the thruster inaddition to the relative orientation of the emerging primary wall jetsat non-parallel angles, facilitating the rapid entrainment and mixingwith the ambient air, whereas the wall jets originating from the linearportion are parallel to each other and less efficient at lower flows.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 illustrates a cross-sectional portion of a fixed-geometrythruster according to an embodiment;

FIG. 2 illustrates a cross-sectional portion of a variable-geometrythruster according to an embodiment;

FIG. 3 illustrates a side perspective view of a variable-geometrythruster according to an embodiment;

FIG. 4 illustrates a side perspective view of variable-geometrycomponents according to an embodiment;

FIG. 5 illustrates a side perspective view of the variable-geometrycomponents in fully open state according to an embodiment;

FIG. 6 illustrates a side perspective view of the variable-geometrycomponents in constricting state according to an embodiment; and

FIG. 7 illustrates a side cross-sectional view of variable-geometrycomponents and a primary fluid passage according to an embodiment.

DETAILED DESCRIPTION

This patent application is intended to describe one or more embodimentsof the present invention. It is to be understood that the use ofabsolute terms, such as “must,” “will,” and the like, as well asspecific quantities, is to be construed as being applicable to one ormore of such embodiments, but not necessarily to all such embodiments.As such, embodiments of the invention may omit, or include amodification of, one or more features or functionalities described inthe context of such absolute terms.

FIG. 1 illustrates a cross-sectional portion of a fixed-geometryCoanda-type thruster 100 including diffusing structure 110. A conduitportion, such as primary fluid area plenum 120, is fixed in itsgeometrical configuration, making the local conditions of the primaryfluid provided by the plenum and the entrainment of secondary fluidintroduced via an intake structure 130 perhaps entirely dependent on theconditions of primary fluid delivery—pressures, flow rates andtemperatures, for example. The performance of the thruster 100 dependson the upstream supply of the primary fluid and may have limited highefficiency at conditions matching the best entrainment and minimallosses. Thruster 100 includes a fixed shim 140 without fringes. Such ageometry may allow ideal performance at a given flow condition or massflow rate, pressure and temperature combination of the primary fluid.

An embodiment includes a Coanda thruster that can change its primaryfluid introduction conditions to match the flow conditions, therebyperforming more efficiently and generating higher entrainment atconditions different from the ideal conditions described with regard toFIG. 1.

Specifically, FIG. 2 illustrates in cross-section, and FIG. 3illustrates in side perspective view, a Coanda-type thruster 200according to an embodiment and similar to thruster 100 illustrated inFIG. 1. Thruster 200 includes a diffusing structure 210 and a conduitportion, such as primary fluid area plenum 220. Plenum 220 suppliesprimary fluid, and an intake structure 230 provides secondary fluid,such as ambient air, to the diffusing structure 210 for mixing of theprimary and secondary fluids therein. The diffusing structure 210comprises a terminal end configured to provide egress from the thruster200 for the mixed primary and secondary fluids. More particularly, andin an embodiment, plenum 220 introduces the primary fluid to a convexCoanda surface 215. The primary fluid may consist of, for non-limitingexample, compressor bleed air from a turbojet or pressurized exhaust gasfrom a gas generator delivered to plenum 220 via a primary-fluid source,such as a duct 250. Thruster 200 further includes a flow controller 240discussed in greater detail below herein.

Referring now to FIG. 4, and in an embodiment, plenum 220 introduces theprimary fluid to the diffusing structure 210 through a series ofpassages 450. Each passage 450 is defined at least in part by arespective wall portion 460. Flow controller 240 includes a series ofconstricting elements, such as shims 440, disposed adjacent acorresponding one of the wall portions 460. The shims 440 may bemanufactured out of a metal material flexible enough and thin enough towithstand multiple cycles of the operation.

Flow controller 240 further includes an actuating apparatus coupled tothe shims 440. The actuating apparatus is configured to urge the shims440 toward their corresponding wall portion 460, thereby reducing thecross-sectional area of each associated passage 450. Additionally, theactuating apparatus may be configured to actively withdraw the shims 440away from their corresponding wall portion 460, thereby increasing thecross-sectional area of each associated passage 450.

In the embodiment illustrated in FIG. 4, the actuating apparatusincludes a primary lever 400 coupled to a series of secondary levers410, each of which is coupled to a corresponding bushing 420. Eachbushing 420 is, in turn, coupled to a corresponding threaded pin 430engaged with threaded slots formed in the intake structure 230. A tip ofeach pin 430 abuts a corresponding one of the shims 440 so as to enabledeflection of the shims toward their corresponding wall portion 460.

As shown in FIG. 5, when the actuating apparatus is in a fully openstate, shims 440 have not been deflected by pins 430 toward walls 460and are at position 700 as illustrated in FIG. 7. Consequently, passage450 is at its maximum cross-sectional area and flow of the primary fluidtherethrough into diffusing structure 210 is minimally constricted.

As shown in FIG. 6, when a force generator (not shown) applies apredetermined motive force to primary lever 400 moving the primary leverhorizontally a corresponding predetermined distance, torque is appliedto each of the secondary levers 410. In response to this applied torque,secondary levers 410 rotate, thereby causing translational movement ofthe tips of pins 430 toward wall portions 460. In turn, shims 440 aredeflected by pins 430 toward wall portions 460 and are at position 710as illustrated in FIG. 7. Consequently, the cross-sectional area ofpassage 450 is decreased and flow of the primary fluid therethrough intodiffusing structure 210 is constricted, and thusly accelerated, to apredetermined degree. Additionally, the injection velocity of theprimary fluid at the wall jet emergence into the ejector 200, whichcontrols the Coanda effect and the entrainment ratio, increases, andhigh performance is maintained even at lower flow rates.

The local increase in velocity decreases the static pressure perBernoulli's principle, allowing more air to be entrained from theambient and resulting in a larger mass flow compared to thefixed-geometry thruster at similar conditions of primary mass flow rate,pressure and temperature.

For instance, a turbine gas generator producing 1 kg/sec of combustiongas at a temperature of 1000 K and 2 bar pressure at 100,000 RPM andsupplying a thruster-ejector designed for these conditions with theprimary fluid produces 150 lbf of thrust. However, the same gasgenerator working at 85,000 RPM speed produces only 0.75 kg/s ofcombustion gas at 950 K and 1.4 bar and the performance of the fixedgeometry primary fluid passage determines a drop in thrust to 100 lbf.The main reason for it is the reduction of the emerging velocity of theprimary fluid into the entrainment area, determining a higher localstatic pressure and therefore less entrainment happens. The changing(reduction) of the primary area to determine a higher local primaryfluid emerging velocity, and according to Bernoulli principle a lowerstatic pressure, increases significantly the entrainment ratio and thethrust to 120 lbf, mainly due to an increase of 20% in the entrainedair.

For those familiar with the subject, the isentropic expansion of theprimary fluid jet results in the ideal thrust value of:

$F_{i} = {\overset{.}{W} \times \sqrt{\left\lbrack {\frac{2\; \gamma}{\gamma - 1} \times R_{u} \times T \times \left( {1 - \left( \frac{P_{\infty}}{P_{t,j}} \right)^{(\frac{\gamma - 1}{\gamma})}} \right)} \right\rbrack}}$

Where {dot over (W)} is the mass flow rate of the primary fluid, γ isthe specific heat coefficient, Ru is the universal gas constant and T isthe temperature, while P are pressures coresponding to the ambient andthe total pressure of the flow. By augmentation ratio, we refer to theratio between the measured thrust and the formula above, calculated forthe respective parameters at hand.

The ability of changing the cross-sectional area of passages 450 isthusly beneficial, improving the overall performance of an otherwisefixed geometry thruster designed for optimal operation only at a certaincondition of the primary fluid (flow, temperature, pressures).

In one embodiment the shims 440 may be manufactured out of stainlesssteel or any other material that can withstand high temperatures of upto 1750 F and still retain elasticity and a life of at least 2000cycles.

The mechanism of moving the pins 430 to reduce the passage 450 area andoptimize the flow may be mechanical in character. However, otheractuation mechanisms could be employed. In an alternative embodiment, amanifold (not shown) may be employed to provide compressed air from asource, such as a compressor or any other high pressure source, toactuate the pins 430 to urge the shims 440 into the flow. Alternatively,electric or magnetic actuators (not shown) could be used to perform thesame function. In yet another embodiment, a mechanism that containslinear and semicircular actuators (not shown) is employed to enable thechange in geometry of various segments or slot blocks of the thruster,adapting it to the conditions at hand.

In another embodiment, the deflection of shims 440 may be such that themechanism completely blocks the flow into all passages, shutting off theflow and cancelling thrust generation at various stages of the flight ofa vehicle. In yet another embodiment, the preferential shutting off ofportions of the primary slots is employed to generate a vectored thrustto reduce the landing distance of an flying vehicle. In yet anotherembodiment, the thruster is used to balance a tailsitter in asymmetrical deployment (i.e., two or more thrusters on the plane oraerial vehicle) and the actuation of the shims 440 allows attitudecontrol of the aircraft in hovering or take off or landing. In yetanother embodiment, a flying car hover is enhanced by employing thevariable geometry feature of the thrusters to control its attitude/speedand can be used for landing or take off or level flight.

Although the foregoing text sets forth a detailed description ofnumerous different embodiments, it should be understood that the scopeof protection is defined by the words of the claims to follow. Thedetailed description is to be construed as exemplary only and does notdescribe every possible embodiment because describing every possibleembodiment would be impractical, if not impossible. Numerous alternativeembodiments could be implemented, using either current technology ortechnology developed after the filing date of this patent, which wouldstill fall within the scope of the claims.

Thus, many modifications and variations may be made in the techniquesand structures described and illustrated herein without departing fromthe spirit and scope of the present claims. For example, in oneembodiment, thruster 200 can be integrated into the induction trackbetween an air filter and a throttle-body/carburetor, and upstream of acylinder or combustion chamber, associated with an internal combustionengine. Alternatively, thruster 200 could be placed in an exhaust pipedownstream of the combustion chamber of an internal combustion engine.Accordingly, it should be understood that the methods and apparatusdescribed herein are illustrative only and are not limiting upon thescope of the claims.

What is claimed is:
 1. A propulsion system coupled to a vehicle, thesystem comprising: a diffusing structure; a conduit portion configuredto introduce to the diffusing structure through a first passage aprimary fluid produced by the vehicle, the first passage being definedby a first wall, wherein the diffusing structure comprises a terminalend configured to provide egress from the system for the introducedprimary fluid; a first constricting element disposed adjacent the firstwall; and an actuating apparatus coupled to the first constrictingelement and configured to urge the first constricting element toward thefirst wall, thereby reducing the cross-sectional area of the firstpassage.
 2. The system of claim 1, wherein the actuating apparatuscomprises: a first translating component configured to engage the firstconstricting element and configured to move translationally; and a firstrotational component coupled to the first translating component andconfigured to move rotationally.
 3. The system of claim 2, wherein theconduit portion is further configured to introduce the primary fluid tothe diffusing structure through a second passage, the second passagebeing defined by a second wall, the system further comprises a secondconstricting element disposed adjacent the second wall, whereby theactuating apparatus is coupled to the second constricting element andconfigured to urge the second constricting element toward the secondwall, thereby reducing the cross-sectional area of the second passage,and the actuating apparatus further comprises: a second translatingcomponent configured to engage the second constricting element andconfigured to move translationally; a second rotational componentcoupled to the second translating component and configured to moverotationally; and a lever element coupled to the first and secondrotational components and configured to rotate the first and secondrotational components in unison.
 4. The system of claim 1, furthercomprising a convex surface coupled to the diffusing structure, whereinthe conduit portion is configured to introduce the primary fluid to theconvex surface through the first passage.
 5. The system of claim 1,wherein the primary fluid comprises compressor bleed air produced by aturbojet.
 6. The system of claim 1, wherein the diffusing structure ispositioned downstream of a turbine of a turbocharger of the vehicle, andthe primary fluid is supplied by the compressor of the turbocharger. 7.A propulsion system coupled to a vehicle, the system comprising: adiffusing structure; an intake structure coupled to the diffusingstructure and configured to introduce to the diffusing structure asecondary fluid accessible to the vehicle, the intake structureincluding a conduit portion configured to introduce to the diffusingstructure through a passage a primary fluid produced by the vehicle, thepassage being defined by a wall, wherein the diffusing structurecomprises a terminal end configured to provide egress from the systemfor the introduced primary fluid and secondary fluid; a firstconstricting element disposed adjacent the wall; and an actuatingapparatus coupled to the constricting element and configured to urge theconstricting element toward the wall, thereby reducing thecross-sectional area of the passage.
 8. The system of claim 7, whereinthe actuating apparatus comprises: a first translating componentconfigured to engage the first constricting element and configured tomove translationally; and a first rotational component coupled to thefirst translating component and configured to move rotationally.
 9. Thesystem of claim 8, wherein the conduit portion is further configured tointroduce the primary fluid to the diffusing structure through a secondpassage, the second passage being defined by a second wall, the systemfurther comprises a second constricting element disposed adjacent thesecond wall, whereby the actuating apparatus is coupled to the secondconstricting element and configured to urge the second constrictingelement toward the second wall, thereby reducing the cross-sectionalarea of the second passage, and the actuating apparatus furthercomprises: a second translating component configured to engage thesecond constricting element and configured to move translationally; asecond rotational component coupled to the second translating componentand configured to move rotationally; and a lever element coupled to thefirst and second rotational components and configured to rotate thefirst and second rotational components in unison.
 10. The system ofclaim 7, further comprising a convex surface coupled to the diffusingstructure, wherein the conduit portion is configured to introduce theprimary fluid to the convex surface through the first passage.
 11. Thesystem of claim 7, wherein the primary fluid comprises compressor bleedair produced by a turbojet.
 12. The system of claim 7, wherein thediffusing structure is positioned downstream of a turbine of aturbocharger of the vehicle, and the primary fluid is supplied by thecompressor of the turbocharger.
 13. A vehicle comprising: aprimary-fluid source; a diffusing structure; a conduit portionconfigured to introduce to the diffusing structure through a firstpassage a primary fluid produced by the source, the first passage beingdefined by a first wall, wherein the diffusing structure comprises aterminal end configured to provide egress from the system for theintroduced primary fluid; a first constricting element disposed adjacentthe first wall; and an actuating apparatus coupled to the firstconstricting element and configured to urge the first constrictingelement toward the first wall, thereby reducing the cross-sectional areaof the first passage.
 14. The vehicle of claim 13, wherein the actuatingapparatus comprises: a first translating component configured to engagethe first constricting element and configured to move translationally;and a first rotational component coupled to the first translatingcomponent and configured to move rotationally.
 15. The vehicle of claim14, wherein the conduit portion is further configured to introduce theprimary fluid to the diffusing structure through a second passage, thesecond passage being defined by a second wall, the system furthercomprises a second constricting element disposed adjacent the secondwall, whereby the actuating apparatus is coupled to the secondconstricting element and configured to urge the second constrictingelement toward the second wall, thereby reducing the cross-sectionalarea of the second passage, and the actuating apparatus furthercomprises: a second translating component configured to engage thesecond constricting element and configured to move translationally; asecond rotational component coupled to the second translating componentand configured to move rotationally; and a lever element coupled to thefirst and second rotational components and configured to rotate thefirst and second rotational components in unison.
 16. The vehicle ofclaim 13, further comprising a convex surface coupled to the diffusingstructure, wherein the conduit portion is configured to introduce theprimary fluid to the convex surface through the first passage.
 17. Thevehicle of claim 13, wherein the vehicle comprises a turbojet, and theprimary fluid comprises compressor bleed air produced by the turbojet.18. The vehicle of claim 13, further comprising a turbocharger, andwherein the diffusing structure is positioned downstream of a turbine ofthe turbocharger, and the primary fluid is supplied by a compressor ofthe turbocharger.
 19. The vehicle of claim 13, further comprising acylinder, wherein the diffusing structure is located upstream of thecylinder.
 20. The vehicle of claim 13, further comprising a cylinder,wherein the diffusing structure is located downstream of the cylinder.